1. Field of the Invention.
The present invention relates to a surgical ventilating apparatus for protecting members of surgical teams from potentially harmful products in the form of vapor and airborne particulates which may issue from an operating zone.
2. Description of the Prior Art.
Since the advent of the discovery that bacterial and other microorganisms cause diseases and that such microorganisms are easily transmitted to a patient's incision from a carrier doctor, unclean instruments or even the air, hospital operating room procedures have incorporated methods to protect the patient by preventing contamination of the operating field and, ultimately, the patient. In particular, sources of patient contamination have included bacteria and other microorganisms shed or exhaled by members of the operating team and protective measures have included masks and other ventilating systems which operate to prevent contaminants shed or exhaled by members of the operating team from entering the surrounding atmosphere and, in particular, from entering the operating field. For example, U.S. Pat. No. 4,055,173 discloses a system for drawing air exhaled by a surgeon and the like away from the surgeon's face so as to limit contamination of the patient.
The Acquired Immunodeficiency Syndrome (AIDS) virus has created a substantial new problem for the surgeon. In particular, no satisfactory method or device has been provided by the prior art to help protect members of the surgical team from airborne contaminants originating in the operating field. These contaminants can and do include the AIDS virus. The current spreading epidemic of AIDS has imposed serious health risks on health care workers subjected to AIDS contaminated blood and body fluids. Such risks are particularly prominent for surgeons in all subspecialties and, also, for other operating room personnel where any drilling, reaming, cutting or the like must occur during an operation, as these processes create an aerosol of the patient's blood, tissue, bone or the like that becomes airborne and which can subsequently settle in a mucus membrane or open wound of a doctor or nurse thereby transmitting the fatal disease to them.
Accidental contamination with airborne aerosols of blood and body fluids of patients having other diseases such as hepatitis B also poses a risk. It has been found that some patients having these diseases have not had the disease for sufficient time to test positive for the disease and hence doctors, even if they test the patient before surgery, are not always warned of the danger.
Studies have identified the principle source of risk to be that associated with inadvertent inoculations through scalpel laceration, needle puncture, splashing and contact of contaminated serum or body fluids with an open wound, conjunctivae or mouth. Such studies are described in J. Bartlett, Testing for HIV Infection: Recommendations for Surgeons, Vol. 73, No. 3, American College of Surgeons Bulletin and G. Telford, et al., A Protocol to Reduce the Risk of Contracting AIDS and Other Blood-Borne Diseases in the OR, March, 1988, Surgical Rounds for Orthopedics.
Guidelines have been proposed to safeguard health care workers in such high risk areas. These consist mainly in recommendations for safe handling of sharp instruments and barrier precautions, including: gloves, face shield, impervious mask and gowns, and foot and leg wear. However, such precautions do not adequately address the risk associated with the effects of spraying and aerosolization of blood, body fluids and tissue during surgical procedures involving the use of many medical operating tools, especially power equipment such as high speed drills, saws and reamers of the type used by orthopedic surgeons and neurosurgeons. Such transmission modes have not been adequately addressed by the previously formulated guidelines.
The extent and effects of spraying and aerosolization of blood, body fluids and tissue during surgical procedures is dependent upon the size, shape and speed of the spray inducing devices and often the spray reaches well beyond the confines of the operating field.
It has been suggested that preoperative testing for the presence of risk-producing contaminants would, by indentifying such contaminants, allow surgeons to take special precautions. However, preoperative testing for patients inflicted with the human immunodeficiency virus (HIV), AIDS related complex (ARC) and hepatitis B has encountered legal constraints and is also problematic in operation. Legal constraints against preoperative testing have arisen because of the controversial nature of such testing. Preoperative testing is problematic because of the serum negative window noted above (i.e. early period in disease cycle when disease is not easily detectable) between exposure and sero positive test results. Preoperative testing is particularly problematic in emergency situations where low but significant percentages of trauma victims are sero positive and there is no time for preoperative testing.
Accordingly, it is highly desirable to confine the potential contaminant to the smallest area possible and, thus, minimize its dissemination and ultimate spread to members of the surgical team. This can be accomplished by creating a negative pressure zone in the field of operation which operates to remove the contaminants before they escape into the surrounding atmosphere. For this purpose, it is important that the low pressure zone be generated by a device which is close to the surgeon's hands, which are almost always at or around the site of the operation without impeding the dexterity or vision of the surgeon.